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Expandable support device and method of use

Expandable support device and method of use description/claims

This application is a continuation of PCT International Application No. PCT/US2006/062201, filed Dec. 15, 2006 which claims the benefit of U.S. Provisional Application No. 60/751,390, filed Dec. 15, 2005, which are both incorporated herein in their entireties.

This invention relates to devices and methods for holding and deploying orthopedic and other expandable support devices (e.g., stents). The expandable support devices can be used for providing support for biological tissue, for example to repair spinal compression fractures.

When performing any medical operation with an implant the implant must be delivered to the treatment site and the implant device must be properly designed and deployed. Important implant device design and deployment characteristics include size, shape, function, material, mechanical properties, and chemical properties, among others.

Vertebroplasty is an image-guided, minimally invasive, nonsurgical therapy used to strengthen a broken vertebra that has been weakened by disease, such as osteoporosis or cancer. Vertebroplasty is often used to treat compression fractures, such as those caused by osteoporosis, cancer, or stress.

Vertebroplasty is often performed on patients too elderly or frail to tolerate open spinal surgery, or with bones too weak for surgical spinal repair. Patients with vertebral damage due to a malignant tumor may sometimes benefit from vertebroplasty. The procedure can also be used in younger patients whose osteoporosis is caused by long-term steroid treatment or a metabolic disorder.

Vertebroplasty can increase the patient's functional abilities, allow a return to the previous level of activity, and prevent further vertebral collapse. Vertebroplasty attempts to also alleviate the pain caused by a compression fracture.

Vertebroplasty is often accomplished by injecting an orthopedic cement mixture through a needle into the fractured bone. The cement mixture can leak from the bone, potentially entering a dangerous location such as the spinal canal. The cement mixture, which is naturally viscous, is difficult to inject through small diameter needles, and thus many practitioners choose to “thin out” the cement mixture to improve cement injection, which ultimately exacerbates the leakage problems. The flow of the cement liquid also naturally follows the path of least resistance once it enters the bone—naturally along the cracks formed during the compression fracture. This further exacerbates the leakage.

The mixture also fills or substantially fills the cavity of the compression fracture and is limited to certain chemical composition, thereby limiting the amount of otherwise beneficial compounds that can be added to the fracture zone to improve healing. Further, a balloon must first be inserted in the compression fracture and the vertebra must be expanded before the cement is injected into the newly formed space.

A vertebroplasty device and method that eliminates or reduces the risks and complexity of the existing art is desired. An easily deployed orthopedic expandable support device that can be controllably delivered and deployed is desired. Being able to recapture the orthopedic expandable support device is also desired.

A deployment system that can include an expandable support device for performing completely implantable spinal repair is disclosed. The expandable support device can be self-expanding. The expandable support device can be deformably expanded by external forces.

The expandable support device can have a first (e.g., distal) end and a second (e.g., proximal) end. The deployment system can control one or both of the first and second ends of the expandable support device until the expandable support device is substantially or completely deployed in a treatment site.

The deployment system can have a threaded rod. The threaded rod can threadably attach to the expandable support device. A compression force can be delivered (e.g., in part) by the rod to the first end of the expandable support device. The threaded rod can release the expandable support device from the remainder of the deployment system, for example by rotating the rod relative to the expandable support device (e.g., unscrewing the rod from the expandable support device). The rod can be reattached (e.g., by screwing) to the expandable support device. The expandable support device can then be repositioned.

The deployment system can have a rod that can have a rod head (e.g., paddle) that can extend through and beyond a distal port in the first end of the expandable support device. The rod head can be larger that the distal port in a first dimension. The rod head can be smaller than the distal port in a second dimension. In a first configuration, the rod head can be interference fit to the first end of the expandable support device. The rod can be rotatable within the distal port. The rod head can deliver a compression force to the first end of the expandable support device. The rod head can engage the expandable support device on one, two or more (e.g., across the entire rod head) points on the first end of the expandable support device.

After the expandable support device is radially expanded using a compressive force, the rod head can be rotated (e.g., about 90 degrees) relative to the expandable support device. The rod can be translated through the expandable support device, removing the rod head. The rod can have a non-round configuration. The non-round rod can guide radial expansion of the expandable support device (e.g., by transmitting torque from the rod to the distal end port's inner walls). Once the stent expandable support device is expanded, the rod and rod head can be turned 90 degrees and the rod's diameter is decreases to release the rod from the stents inside walls.

The deployment system can have a rod that can have a wedge-shaped rod head. The rod head can be retractable into the rod, for example to withdraw the rod through the distal port in the expandable support device. The retraction of the rod head can be resisted by a spring, for example, to prevent retraction of the rod head before deployment. The rod head retraction can be remotely (e.g., mechanically or electrically) controlled.

The deployment system can be covered by a sheath. The sheath can constrain radial expansion of the expandable support device. The sheath can slide or otherwise translate off of the expandable support device and/or a pusher or driver can force the expandable support device out of the open end of the sheath. The sheath can self-expand and/or be deformably expanded once completely or partially out of the sheath.

The deployment system can have a rod that can have a pin. The rod can have a pin attached to, and extending radially from, the rod. In pre-deployment and compression configurations, the pin can be constrained by the expandable support device. Once the expandable support device is radially expanded, the pin and/or expandable support device can deform out of the constrained configuration and/or the ends of the pin can shear off, detaching the expandable support device and the deployment system.

A method for repairing a damaged section of a spine is also disclosed. The method includes expanding the expandable support device in the damaged section.

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• Utility Patent

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